Flats and filters

[GrampyG]

Can flats be taken with a filter fitted or must there be a clear optical train?

Thank you

G

[Snoani]

They can and should be taken for each and every filter used.

Jem

[teoria_del_big_bang]

I am afraid you will probably get replies with differing ideas.

I would agree with @Snoani and I do take flats for each filter used during that session and if possible take them every morning after a session and not rely on flats from previous sessions.
The idea being that dust bunnies can change from day to day and they will be different on each filter.
But, i also have never done any tests to see if using one set of fats would make a significant difference to the final image, I always just used the logic that if I can do them easily for each filter then it can't do any harm 🙂 

After saying that others only use one set of flats from either Lum or Ha and others even use flasts from previous nights so long as the camera, FW etc are at the same angle as previous nights and with great results. So up to you see what works for you. My personal preference , so long as I have time is to do them for all filters as I use a flat field generator and so is a pretty quick affair. If using white T Shirt and natural light then may not always be easily possible so then you may have to use previous flats.

Steve

Edited January 10, 2021 by teoria_del_big_bang

[GrampyG]

Hi

Thank you for your replies.

Just taken some flats with the filters I have recently acquired. I've used an LED panel (daylight)- I've found this to be successful in the past. So I'll see what happens.

Thank you once again

G